在RAC切换到单实例DG后，将OGG目录复制过去，在使用alter extract ext_name,begin now的时候报错
2016-04-10 11:27:03 WARNING OGG-01423 Oracle GoldenGate Capture for Oracle, cknm2bet.prm: No valid default archive log destination directory found 2016-04-10 11:27:03 INFO OGG-00546 Oracle GoldenGate Capture for Oracle, cknm2bet.prm: Default thread stack size: 10485760. 2016-04-10 11:27:03 ERROR OGG-00446 Oracle GoldenGate Capture for Oracle, cknm2bet.prm: The number of Oracle redo threads (2) is not the same 2016-04-10 11:27:03 ERROR OGG-01668 Oracle GoldenGate Capture for Oracle, cknm2bet.prm: PROCESS ABENDING.
原因是以前是RAC，因此有两个thread，产生的redo是两个，现在是单实例，只有一个thread，只是产生一个redo
解决方法：
select THREAD#, STATUS , ENABLED , SEQUENCE#, to_char(LAST_REDO_TIME,'dd-mon-yy hh24:mi:ss') from v$thread;
THREAD# STATUS ENABLED SEQUENCE# TO_CHAR(LAST_REDO_TIME,'DD-
---------- ------ -------- ---------- ---------------------------
1 OPEN PUBLIC 62 17-apr-20 17:11:21
2 CLOSED PUBLIC 38 15-apr-20 15:00:42
select THREAD#,GROUP#,SEQUENCE#,MEMBERS,status from v$log order by SEQUENCE#;
THREAD# GROUP# SEQUENCE# MEMBERS STATUS
---------- ---------- ---------- ---------- ----------------
2 4 0 1 UNUSED
2 3 38 1 INACTIVE
1 2 61 1 INACTIVE
1 1 62 1 CURRENT 禁用thread2 alter database disable thread 2; 删除thread2的logfile（unused） alter database drop logfile group 4;
alter database drop logfile group 3; ggsc> alter extract ext_name, thread 1, extseqno 547, extrba 0;